1. Field of the Invention
The present invention relates to a cleaning member which removes toner from a transfer roller for transferring a toner image on an image bearing member onto a recording material.
2. Description of the Related Art
In the field of an image forming apparatus, in particular, in a color image forming apparatus, an intermediate transfer system using an electronic photosensitive drum (to be referred as a photosensitive drum hereinafter) serving as an image bearing member or an endless intermediate transfer belt is frequently used. More specifically, a toner image obtained by developing an electrostatic latent image on the photosensitive drum with toner is temporarily transferred (primary transfer) on an intermediate transfer belt. The primary-transferred image is transferred (secondary transfer) on a sheet such as paper serving as a transferred material (recording material) fed to a nip portion between the intermediate transfer belt and a secondary transfer roller being in press contact with the intermediate transfer belt. The secondary transfer roller is brought into contact with an intermediate transfer belt. On the other hand, when the secondary transferring operation is not performed, the secondary transfer roller is separated from the intermediate transfer belt to reduce deterioration of the secondary transfer belt and the intermediate transfer belt. In execution of the secondary transferring operation, electric charges to form a transfer electric field are given to the secondary transfer roller, and the toner image is transferred from the intermediate transfer belt onto the sheet by a pressing force obtained by the transfer electric field and the secondary transfer roller.
In this case, in the image forming apparatus, when toner adheres to the secondary transfer roller, the toner is transferred onto the sheet in the secondary transferring operation to create a stain on the rear surface.
For this reason, a voltage is applied to a cleaning member being in contact with the rotating secondary transfer roller to cause a cleaning current to flow between the secondary transfer roller and the cleaning member so as to remove the toner adhering to the secondary transfer roller. In order to improve cleaning capability, the toner is removed from the secondary transfer roller when the secondary transfer roller is in contact with the intermediate transfer member and when the secondary transfer roller is separated from the intermediate transfer member.
However, when the secondary transfer roller is separated from the intermediate transfer belt, it is disadvantageously impossible to sufficiently remove the toner in the removal of toner from the secondary transfer roller.
More specifically, when the secondary transfer roller rotates while being in contact with the intermediate transfer member and rotated, rotation of the secondary transfer roller is adversely influenced by a rotating torque of the intermediate transfer member. When the secondary transfer roller is separated from the intermediate transfer belt, the secondary transfer roller is released from the influence of the go-around of the intermediate transfer belt, and a rotational velocity of the secondary transfer roller changes. With the change in rotational velocity, toner removal cannot be easily sufficiently removed.